AgdaPkt 2012-02-06 - Laserfiche WebLink

Browse Search

6.1.A. - Page 19 modifieations will be incorporated inta the 1 �D% Finalized Plans, Calculations and Specifi�ations. All comments shall be either incorporated, or respanded �o if not inearporated. Gansu6tant st�a�l finalize all construction documents for �idding �i.e., plans and specifications) and shall fi�alize the Er�gEneer's Cast Estimate. Task �b. Pipes at Share�ird Island and Bridge Park�nray Bridges There is a 8-inch diameter water pipe that is supported an the existi�g (c. 1981-vir�tage) Shore�iird Island bridge in �Z�dwoad Shores. B�sed on pre�iminary review, the bridge is 3-span, a pile supp�rt structure, with deCks having rol�er-pinned type s�u�ports; the pipe is �teel, supported by roller-type supports and is supparted far deadweight loads. The pipe goes throug� the pier caps though �r�pty annulus, requiring mit�r be�d� Fn th� pipe to accommodate actual annulus locations. Pipe girth }oint conn�ctivns are made �s�n� Dresser-typ� slip cc�uplin� units. There is concern the pip� may fail unde� ��ismic loads. This might happen due ta ir�ertial loading an �he pi�e; differ�ntial mc�vement between the bridge decks 1 pi�r caps and the pipe; thrus� farces; abutment movements. There is a 16-ir�ch diameter water pipe that is supported on the existing Bridge Par�Cway �ridge in Redwood Shores_ Based on recent inspections, one o# the pipe joints has failed. There is concern tl�at seismic loads wauld aggravate the situ�tion. Cons�tltant will evaluate the pipes ta allow them to perform after a large earthq�ake on either the nearby San Andreas or Hayward faults. Using ALA (2005) termino�vgy, Consultant will con�ider the pipes as Category III (important} pipe, designed for seismic effects considered a 975-year r�turn period motion. Approach � Consultant will in�pect the pipes and bridges at the two �ites. Consultant will then esta�lish site-specific seismi� ground motions, considering grQUnd shaking {975- years) and poter�tial �or permanent grourrd defflrmations (settlements and late� spreads}. Consultant will use existing subsurFace information for Redwood Shores (original Fte�wood ShAr�s development data, plus loeal soils report by Cooper Clarlc, if available), supplemented with any extra subsurfaee information made available to us. Cansultant will eval�ate the c�mbined existin� bridge — pipe system for thermal and seismic effects. Gansultant will examine the stresses in the pipe; deformation �t pipe joir�ts along the bridge; and impacts to the pipe at either bridge abutment. Gonsultant will try to establish the likely cause(s) of the damaged wat�r pipe joint on the Bridge Parkway bridge. Gflnsultant will also assess the likely performance of the bridge, as if pertains to t�e perFormance o# the pip�s. Consultant will establish the adec�uacy of the as-is system (likely nat); and also pro�ide upgrade optiflns, including: • Madifiy pipe suppor#s an the bridge � Modify pipe (change of jvints; etc,) an the bridge and appraaches. For the 16'° pipe on the Br�dge Parkway bridge, Cons�ultant will devslop a repair strategy for the pipe that has already had a damaged joint. ATTYl�4GR12012.0011G&E �V�fGIC�EERING Page 15 of 3Q R�v�n�r�nri�